<?php

/**
 * @file
 * Field forms management.
 */

/**
 * Create a separate form element for each field.
 */
function field_default_form($entity_type, $entity, $field, $instance, $langcode, $items, &$form, &$form_state, $get_delta = NULL) {
	// This could be called with no entity, as when a UI module creates a
	// dummy form to set default values.
	if ($entity) {
		list($id, , ) = entity_extract_ids($entity_type, $entity);
	}

	$parents = $form['#parents'];

	$addition = array();
	$field_name = $field['field_name'];
	$addition[$field_name] = array();

	// Populate widgets with default values when creating a new entity.
	if (empty($items) && empty($id)) {
		$items = field_get_default_value($entity_type, $entity, $field, $instance, $langcode);
	}

	// Let modules alter the widget properties.
	$context = array(
			'entity_type' => $entity_type,
			'entity' => $entity,
			'field' => $field,
			'instance' => $instance,
	);
	drupal_alter(array('field_widget_properties', 'field_widget_properties_' . $entity_type), $instance['widget'], $context);

	// Collect widget elements.
	$elements = array();
	if (field_access('edit', $field, $entity_type, $entity)) {
		// Store field information in $form_state.
		if (!field_form_get_state($parents, $field_name, $langcode, $form_state)) {
			$field_state = array(
					'field' => $field,
					'instance' => $instance,
					'items_count' => count($items),
					'array_parents' => array(),
					'errors' => array(),
			);
			field_form_set_state($parents, $field_name, $langcode, $form_state, $field_state);
		}

		// If field module handles multiple values for this form element, and we
		// are displaying an individual element, process the multiple value form.
		if (!isset($get_delta) && field_behaviors_widget('multiple values', $instance) == FIELD_BEHAVIOR_DEFAULT) {
			$elements = field_multiple_value_form($field, $instance, $langcode, $items, $form, $form_state);
		}
		// If the widget is handling multiple values (e.g Options), or if we are
		// displaying an individual element, just get a single form element and
		// make it the $delta value.
		else {
			$delta = isset($get_delta) ? $get_delta : 0;
			$function = $instance['widget']['module'] . '_field_widget_form';
			if (function_exists($function)) {
				$element = array(
						'#entity_type' => $instance['entity_type'],
						'#bundle' => $instance['bundle'],
						'#field_name' => $field_name,
						'#language' => $langcode,
						'#field_parents' => $parents,
						'#columns' => array_keys($field['columns']),
						'#title' => check_plain($instance['label']),
						'#description' => field_filter_xss($instance['description']),
						// Only the first widget should be required.
						'#required' => $delta == 0 && $instance['required'],
						'#delta' => $delta,
				);
				if ($element = $function($form, $form_state, $field, $instance, $langcode, $items, $delta, $element)) {
					// Allow modules to alter the field widget form element.
					$context = array(
							'form' => $form,
							'field' => $field,
							'instance' => $instance,
							'langcode' => $langcode,
							'items' => $items,
							'delta' => $delta,
					);
					drupal_alter(array('field_widget_form', 'field_widget_' . $instance['widget']['type'] . '_form'), $element, $form_state, $context);

					// If we're processing a specific delta value for a field where the
					// field module handles multiples, set the delta in the result.
					// For fields that handle their own processing, we can't make
					// assumptions about how the field is structured, just merge in the
					// returned element.
					if (field_behaviors_widget('multiple values', $instance) == FIELD_BEHAVIOR_DEFAULT) {
						$elements[$delta] = $element;
					}
					else {
						$elements = $element;
					}
				}
			}
		}
	}

	if ($elements) {
		// Also aid in theming of field widgets by rendering a classified
		// container.
		$addition[$field_name] = array(
				'#type' => 'container',
				'#attributes' => array(
						'class' => array(
								'field-type-' . drupal_html_class($field['type']),
								'field-name-' . drupal_html_class($field_name),
								'field-widget-' . drupal_html_class($instance['widget']['type']),
						),
				),
				'#weight' => $instance['widget']['weight'],
		);
	}

	// Populate the 'array_parents' information in $form_state['field'] after
	// the form is built, so that we catch changes in the form structure performed
	// in alter() hooks.
	$elements['#after_build'][] = 'field_form_element_after_build';
	$elements['#field_name'] = $field_name;
	$elements['#language'] = $langcode;
	$elements['#field_parents'] = $parents;

	$addition[$field_name] += array(
			'#tree' => TRUE,
			// The '#language' key can be used to access the field's form element
			// when $langcode is unknown.
			'#language' => $langcode,
			$langcode => $elements,
	);

	return $addition;
}

/**
 * Special handling to create form elements for multiple values.
 *
 * Handles generic features for multiple fields:
 * - number of widgets
 * - AHAH-'add more' button
 * - drag-n-drop value reordering
 */
function field_multiple_value_form($field, $instance, $langcode, $items, &$form, &$form_state) {
	$field_name = $field['field_name'];
	$parents = $form['#parents'];

	// Determine the number of widgets to display.
	switch ($field['cardinality']) {
		case FIELD_CARDINALITY_UNLIMITED:
			$field_state = field_form_get_state($parents, $field_name, $langcode, $form_state);
			$max = $field_state['items_count'];
			break;

		default:
			$max = $field['cardinality'] - 1;
			break;
	}

	$title = check_plain($instance['label']);
	$description = field_filter_xss($instance['description']);

	$id_prefix = implode('-', array_merge($parents, array($field_name)));
	$wrapper_id = drupal_html_id($id_prefix . '-add-more-wrapper');

	$field_elements = array();

	$function = $instance['widget']['module'] . '_field_widget_form';
	if (function_exists($function)) {
		for ($delta = 0; $delta <= $max; $delta++) {
			$multiple = $field['cardinality'] > 1 || $field['cardinality'] == FIELD_CARDINALITY_UNLIMITED;
			$element = array(
					'#entity_type' => $instance['entity_type'],
					'#bundle' => $instance['bundle'],
					'#field_name' => $field_name,
					'#language' => $langcode,
					'#field_parents' => $parents,
					'#columns' => array_keys($field['columns']),
					// For multiple fields, title and description are handled by the wrapping table.
					'#title' => $multiple ? '' : $title,
					'#description' => $multiple ? '' : $description,
					// Only the first widget should be required.
					'#required' => $delta == 0 && $instance['required'],
					'#delta' => $delta,
					'#weight' => $delta,
			);
			if ($element = $function($form, $form_state, $field, $instance, $langcode, $items, $delta, $element)) {
				// Input field for the delta (drag-n-drop reordering).
				if ($multiple) {
					// We name the element '_weight' to avoid clashing with elements
					// defined by widget.
					$element['_weight'] = array(
							'#type' => 'weight',
							'#title' => t('Weight for row @number', array('@number' => $delta + 1)),
							'#title_display' => 'invisible',
							// Note: this 'delta' is the FAPI 'weight' element's property.
							'#delta' => $max,
							'#default_value' => isset($items[$delta]['_weight']) ? $items[$delta]['_weight'] : $delta,
							'#weight' => 100,
					);
				}

				// Allow modules to alter the field widget form element.
				$context = array(
						'form' => $form,
						'field' => $field,
						'instance' => $instance,
						'langcode' => $langcode,
						'items' => $items,
						'delta' => $delta,
				);
				drupal_alter(array('field_widget_form', 'field_widget_' . $instance['widget']['type'] . '_form'), $element, $form_state, $context);

				$field_elements[$delta] = $element;
			}
		}

		if ($field_elements) {
			$field_elements += array(
					'#theme' => 'field_multiple_value_form',
					'#field_name' => $field['field_name'],
					'#cardinality' => $field['cardinality'],
					'#title' => $title,
					'#required' => $instance['required'],
					'#description' => $description,
					'#prefix' => '<div id="' . $wrapper_id . '">',
					'#suffix' => '</div>',
					'#max_delta' => $max,
			);
			// Add 'add more' button, if not working with a programmed form.
			if ($field['cardinality'] == FIELD_CARDINALITY_UNLIMITED && empty($form_state['programmed'])) {
				$field_elements['add_more'] = array(
						'#type' => 'submit',
						'#name' => strtr($id_prefix, '-', '_') . '_add_more',
						'#value' => t('Add another item'),
						'#attributes' => array('class' => array('field-add-more-submit')),
						'#limit_validation_errors' => array(array_merge($parents, array($field_name, $langcode))),
						'#submit' => array('field_add_more_submit'),
						'#ajax' => array(
								'callback' => 'field_add_more_js',
								'wrapper' => $wrapper_id,
								'effect' => 'fade',
						),
				);
			}
		}
	}

	return $field_elements;
}

/**
 * Returns HTML for an individual form element.
 *
 * Combine multiple values into a table with drag-n-drop reordering.
 * TODO : convert to a template.
 *
 * @param $variables
 *   An associative array containing:
 *   - element: A render element representing the form element.
 *
 * @ingroup themeable
 */
function theme_field_multiple_value_form($variables) {
	$element = $variables['element'];
	$output = '';

	if ($element['#cardinality'] > 1 || $element['#cardinality'] == FIELD_CARDINALITY_UNLIMITED) {
		$table_id = drupal_html_id($element['#field_name'] . '_values');
		$order_class = $element['#field_name'] . '-delta-order';
		$required = !empty($element['#required']) ? theme('form_required_marker', $variables) : '';

		$header = array(
				array(
						'data' => '<label>' . t('!title: !required', array('!title' => $element['#title'], '!required' => $required)) . "</label>",
						'colspan' => 2,
						'class' => array('field-label'),
				),
				t('Order'),
		);
		$rows = array();

		// Sort items according to '_weight' (needed when the form comes back after
		// preview or failed validation)
		$items = array();
		foreach (element_children($element) as $key) {
			if ($key === 'add_more') {
				$add_more_button = &$element[$key];
			}
			else {
				$items[] = &$element[$key];
			}
		}
		usort($items, '_field_sort_items_value_helper');

		// Add the items as table rows.
		foreach ($items as $key => $item) {
			$item['_weight']['#attributes']['class'] = array($order_class);
			$delta_element = drupal_render($item['_weight']);
			$cells = array(
					array('data' => '', 'class' => array('field-multiple-drag')),
					drupal_render($item),
					array('data' => $delta_element, 'class' => array('delta-order')),
			);
			$rows[] = array(
					'data' => $cells,
					'class' => array('draggable'),
			);
		}

		$output = '<div class="form-item">';
		$output .= theme('table', array('header' => $header, 'rows' => $rows, 'attributes' => array('id' => $table_id, 'class' => array('field-multiple-table'))));
		$output .= $element['#description'] ? '<div class="description">' . $element['#description'] . '</div>' : '';
		$output .= '<div class="clearfix">' . drupal_render($add_more_button) . '</div>';
		$output .= '</div>';

		drupal_add_tabledrag($table_id, 'order', 'sibling', $order_class);
	}
	else {
		foreach (element_children($element) as $key) {
			$output .= drupal_render($element[$key]);
		}
	}

	return $output;
}

/**
 * #after_build callback for field elements in a form.
 *
 * This stores the final location of the field within the form structure so
 * that field_default_form_errors() can assign validation errors to the right
 * form element.
 *
 * @see field_default_form_errors()
 */
function field_form_element_after_build($element, &$form_state) {
	$parents = $element['#field_parents'];
	$field_name = $element['#field_name'];
	$langcode = $element['#language'];

	$field_state = field_form_get_state($parents, $field_name, $langcode, $form_state);
	$field_state['array_parents'] = $element['#array_parents'];
	field_form_set_state($parents, $field_name, $langcode, $form_state, $field_state);

	return $element;
}

/**
 * Transfer field-level validation errors to widgets.
 */
function field_default_form_errors($entity_type, $entity, $field, $instance, $langcode, $items, $form, &$form_state) {
	$field_state = field_form_get_state($form['#parents'], $field['field_name'], $langcode, $form_state);

	if (!empty($field_state['errors'])) {
		$function = $instance['widget']['module'] . '_field_widget_error';
		$function_exists = function_exists($function);

		// Locate the correct element in the the form.
		$element = drupal_array_get_nested_value($form_state['complete form'], $field_state['array_parents']);

		$multiple_widget = field_behaviors_widget('multiple values', $instance) != FIELD_BEHAVIOR_DEFAULT;
		foreach ($field_state['errors'] as $delta => $delta_errors) {
			// For multiple single-value widgets, pass errors by delta.
			// For a multiple-value widget, all errors are passed to the main widget.
			$error_element = $multiple_widget ? $element : $element[$delta];
			foreach ($delta_errors as $error) {
				if ($function_exists) {
					$function($error_element, $error, $form, $form_state);
				}
				else {
					// Make sure that errors are reported (even incorrectly flagged) if
					// the widget module fails to implement hook_field_widget_error().
					form_error($error_element, $error['error']);
				}
			}
		}
		// Reinitialize the errors list for the next submit.
		$field_state['errors'] = array();
		field_form_set_state($form['#parents'], $field['field_name'], $langcode, $form_state, $field_state);
	}
}

/**
 * Submit handler for the "Add another item" button of a field form.
 *
 * This handler is run regardless of whether JS is enabled or not. It makes
 * changes to the form state. If the button was clicked with JS disabled, then
 * the page is reloaded with the complete rebuilt form. If the button was
 * clicked with JS enabled, then ajax_form_callback() calls field_add_more_js()
 * to return just the changed part of the form.
 */
function field_add_more_submit($form, &$form_state) {
	$button = $form_state['triggering_element'];

	// Go one level up in the form, to the widgets container.
	$element = drupal_array_get_nested_value($form, array_slice($button['#array_parents'], 0, -1));
	$field_name = $element['#field_name'];
	$langcode = $element['#language'];
	$parents = $element['#field_parents'];

	// Increment the items count.
	$field_state = field_form_get_state($parents, $field_name, $langcode, $form_state);
	$field_state['items_count']++;
	field_form_set_state($parents, $field_name, $langcode, $form_state, $field_state);

	$form_state['rebuild'] = TRUE;
}

/**
 * Ajax callback in response to a new empty widget being added to the form.
 *
 * This returns the new page content to replace the page content made obsolete
 * by the form submission.
 *
 * @see field_add_more_submit()
 */
function field_add_more_js($form, $form_state) {
	$button = $form_state['triggering_element'];

	// Go one level up in the form, to the widgets container.
	$element = drupal_array_get_nested_value($form, array_slice($button['#array_parents'], 0, -1));
	$field_name = $element['#field_name'];
	$langcode = $element['#language'];
	$parents = $element['#field_parents'];

	$field_state = field_form_get_state($parents, $field_name, $langcode, $form_state);

	$field = $field_state['field'];
	if ($field['cardinality'] != FIELD_CARDINALITY_UNLIMITED) {
		return;
	}

	// Add a DIV around the delta receiving the Ajax effect.
	$delta = $element['#max_delta'];
	$element[$delta]['#prefix'] = '<div class="ajax-new-content">' . (isset($element[$delta]['#prefix']) ? $element[$delta]['#prefix'] : '');
	$element[$delta]['#suffix'] = (isset($element[$delta]['#suffix']) ? $element[$delta]['#suffix'] : '') . '</div>';

	return $element;
}

/**
 * Retrieves processing information about a field from $form_state.
 *
 * @param $parents
 *   The array of #parents where the field lives in the form.
 * @param $field_name
 *   The field name.
 * @param $langcode
 *   The language in which the field values are entered.
 * @param $form_state
 *   The form state.
 *
 * @return
 *   An array with the following key/data pairs:
 *   - field: the field definition array,
 *   - instance: the field instance definition array,
 *   - items_count: the number of widgets to display for the field,
 *   - array_parents: the location of the field's widgets within the $form
 *     structure. This entry is populated at '#after_build' time.
 *   - errors: the array of field validation errors reported on the field. This
 *     entry is populated at field_attach_form_validate() time.
 *
 * @see field_form_set_state()
 */
function field_form_get_state($parents, $field_name, $langcode, &$form_state) {
	$form_state_parents = _field_form_state_parents($parents, $field_name, $langcode);
	return drupal_array_get_nested_value($form_state, $form_state_parents);
}

/**
 * Stores processing information about a field in $form_state.
 *
 * @param $parents
 *   The array of #parents where the field lives in the form.
 * @param $field_name
 *   The field name.
 * @param $langcode
 *   The language in which the field values are entered.
 * @param $form_state
 *   The form state.
 * @param $field_state
 *   The array of data to store. See field_form_get_state() for the structure
 *   and content of the array.
 *
 * @see field_form_get_state()
 */
function field_form_set_state($parents, $field_name, $langcode, &$form_state, $field_state) {
	$form_state_parents = _field_form_state_parents($parents, $field_name, $langcode);
	drupal_array_set_nested_value($form_state, $form_state_parents, $field_state);
}

/**
 * Returns the location of processing information within $form_state.
 */
function _field_form_state_parents($parents, $field_name, $langcode) {
	// To ensure backwards compatibility on regular entity forms for widgets that
	// still access $form_state['field'][$field_name] directly,
	// - top-level fields (empty $parents) are placed directly under
	//   $form_state['fields'][$field_name].
	// - Other fields are placed under
	//   $form_state['field']['#parents'][...$parents...]['#fields'][$field_name]
	//   to avoid clashes between field names and $parents parts.
	// @todo Remove backwards compatibility in Drupal 8, and use a unique
	// $form_state['field'][...$parents...]['#fields'][$field_name] structure.
	if (!empty($parents)) {
		$form_state_parents = array_merge(array('#parents'), $parents, array('#fields'));
	}
	else {
		$form_state_parents = array();
	}
	$form_state_parents = array_merge(array('field'), $form_state_parents, array($field_name, $langcode));

	return $form_state_parents;
}

/**
 * Retrieves the field definition for a widget's helper callbacks.
 *
 * Widgets helper element callbacks (such as #process, #element_validate,
 * #value_callback, ...) should use field_widget_field() and
 * field_widget_instance() instead of field_info_field() and
 * field_info_instance() when they need to access field or instance properties.
 * See hook_field_widget_form() for more details.
 *
 * @param $element
 *   The structured array for the widget.
 * @param $form_state
 *   The form state.
 *
 * @return
 *   The $field definition array for the current widget.
 *
 * @see field_widget_instance()
 * @see hook_field_widget_form()
 */
function field_widget_field($element, $form_state) {
	$field_state = field_form_get_state($element['#field_parents'], $element['#field_name'], $element['#language'], $form_state);
	return $field_state['field'];
}

/**
 * Retrieves the instance definition array for a widget's helper callbacks.
 *
 * Widgets helper element callbacks (such as #process, #element_validate,
 * #value_callback, ...) should use field_widget_field() and
 * field_widget_instance() instead of field_info_field() and
 * field_info_instance() when they need to access field or instance properties.
 * See hook_field_widget_form() for more details.
 *
 * @param $element
 *   The structured array for the widget.
 * @param $form_state
 *   The form state.
 *
 * @return
 *   The $instance definition array for the current widget.
 *
 * @see field_widget_field()
 * @see hook_field_widget_form()
 */
function field_widget_instance($element, $form_state) {
	$field_state = field_form_get_state($element['#field_parents'], $element['#field_name'], $element['#language'], $form_state);
	return $field_state['instance'];
}
